TORONTO, June 4 (Reuters) - Canada’s main stock market index closed above the 20,000 level for the first time on Friday as higher commodity prices bolstered the shares of resource companies. The Toronto Stock Exchange’s S&P/TSX composite index unofficially closed up 87.80 points, or 0.4%, at 20,029.19. Investors say that 20,000 is a key psychological level. (Reporting by Fergal Smith) Our Standards: The Thomson Reuters Trust Principles.